1. Field of the Invention
The present invention relates to network protectors and, more specifically, to a retrofit handle assembly structured to allow one type of network protector circuit breaker to be used in a tank structured for a different type of network protector circuit breaker.
2. Background Information
Secondary power distribution networks consist of interlaced grids which are supplied by two or more sources of power so that the loss of a single source of power will not result in an interruption of service. Such secondary power distribution networks provide the highest level of reliability possible with conventional power distribution and are normally used to supply high-density load areas such as a section of a city, a large building, or an industrial site. Between a power source and the network is a transformer and a network protector. The network protector consists of a circuit breaker and a control relay. The circuit breaker includes at least one set of main contacts that move between an open position and a closed position. When the main contacts are closed, electricity may flow through the network protector. The control relay senses the transformer and network voltages and line currents then executes algorithms to initiate a tripping or closing action. Trip determination is based on detecting an overcurrent condition or reverse power flow, that is, power flow from the network to the energy source. Network protectors are often found in dust-proof and/or moisture-proof housings, or vaults, which are disposed in subterranean passageways in large metropolitan areas. More specifically, an enclosure, or “tank,” is disposed with the vault and the network protector is disposed within the tank.
The network protector circuit breaker includes a number of other components such as, but not limited to, a bus assembly, an operating mechanism structured to move the contacts between the open position and the closed position, and a frame assembly. Typically, a close device may be either a non-stored energy device, wherein a motor or other device closes the contacts, or a stored energy device, wherein springs, which are compressed by a motor or by a crank, are used to close the main contacts. The frame assembly supports the circuit breaker and is structured to engage the tank. In a “roll-out” configuration, the tank includes a set of rails that may be extended from the tank and the frame assembly includes rollers which are disposed upon the rails. In this configuration, the circuit breaker may easily be moved into, and out of, the tank.
The tank includes a number of components that are coupled to the network protector components, or, that extend between the network protector and other elements of the power distribution network. For example, the tank includes a bus assembly having a line assembly and a load assembly. The tank bus assembly is structured to be coupled to the circuit breaker bus assembly so that electricity may flow through the network protector. The tank may also include an external operating handle. The operating handle is coupled to the circuit breaker operating mechanism shaft and is structured to actuate the operating mechanism. Generally, the operating handle may be moved to an “open” position wherein the circuit breaker operating shaft is rotated so that the contacts separate. During normal operation of the circuit breaker, the operating handle is set in an “automatic” position wherein the contacts are closed, but may be opened by the circuit breaker trip device or by an operator moving the handle to the open position. After the contacts have been opened, the operating handle may be moved to a “close” position wherein the contacts are moved in to the closed position and, typically, the trip device is reset. After the contacts have been closed, the operating handle is, typically, returned to the automatic position. Each of these components, as well as others, are structured to operate/engage a specific type of circuit breaker.
That is, the tank is structured to have a specific type of circuit breaker with components in a specific configuration disposed therein. Each type of circuit breaker, while generally performing the same function, includes various different components. For example, a CM22 type circuit breaker tank includes an operating handle that is structured to engage a CM22 type circuit breaker. Conversely, an MG 8 or 9 type circuit breaker tank includes an operating handle that is structured to engage a MG 8 or 9 type circuit breaker. Generally, a certain type of circuit breaker is not structured to be placed into a different type of circuit breaker tank. This is a disadvantage as older circuit breakers, such as the MG 8 or 9 type circuit breaker needs to be replaced and customers, typically, desire to have a newer type of circuit breaker, such as the CM22 type circuit breaker, installed.
While some changes, such as changes to the circuit breaker frame assembly, are relatively easy to accomplish, other changes require a retrofit device or assembly so that the tank for one type of circuit breaker may interface with the components of another type of circuit breaker. More specifically, there is a need for a retrofit operating handle assembly structured to allow a CM22 type circuit breaker to be operatively coupled to a MG 8 or 9 type circuit breaker tank.